Three more people were rescued from the blazing building in Backnang, a town near Stuttgart, among them the children's grandmother. The family was of Turkish origin.

Authorities were alerted to the blaze in the early hours of Sunday.

Once it had been brought under control, firefighters found the bodies of the 40-year-old woman and seven of her 10 children, aged between six months and 16 years, in two rooms of their second-floor apartment.

The victims' names were not released.

Police and prosecutors said the fire almost certainly broke out in the apartment. A heater was a focus of investigations.

A German-Turkish cultural association has an office on the building's ground floor.

Police said there was no indication that the fire might have been set deliberately or been a racist attack.

The building is part of a former leather factory that was converted into a row of three-storey apartment blocks.